88 HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. 



and this was a very short one. To make sure that the 

 pollen was good, I took in this case, and in most of 

 the other cases, pollen either from the same anther or 

 from the same flower, and proved it to be good by 

 placing it on the stigma of a short-styled plant, and 

 found numerous pollen-tubes emitted. 



Thirdly. Eepeated last experiment, and placed own- 

 form pollen on all five stigmas of a long-styled flower; 

 after nineteen hours and a half, not one single grain 

 had emitted its tube. 



Fourthly. Eepeated the experiment, with the same 

 result after twenty-four hours. 



Fifthly. Eepeated last experiment, and, after leaving 

 pollen on for nineteen hours, put on an additional 

 quantity of own-form pollen on all five stigmas. After 

 an interval of three days, the stigmas were examined, 

 and, instead of being discoloured and twisted, they 

 were straight and fresh-coloured. Only one grain had 

 emitted a quite short tube, which was drawn out of 

 the stigmatic tissue without being ruptured. 



The following experiments are more striking: 



Sixthly. I placed own-form pollen on three of the 

 stigmas of the long-styled flower, and pollen from a 

 short-styled flower on the other two stigmas. After 

 twenty-two hours these two stigmas were discoloured, 

 slightly twisted, and penetrated by the tubes of nu- 

 merous pollen-grains: the other three stigmas, covered 

 with their own-form pollen, were fresh, and all the 

 pollen-grains were loose ; but I did not dissect the whole 

 stigma. 



Seventhly. Experiment repeated in the same man- 

 ner, with the same result. 



Eighthly. Experiment repeated, but the stigmas were 

 carefully examined after an interval of only five hours 

 and a half. The two stigmas with pollen from a short- 



